[media] davinci: remove VPBE_ENC_DV_PRESET and rename VPBE_ENC_CUSTOM_TIMINGS

Remove VPBE_ENC_DV_PRESET (the DV_PRESET API is no longer supported) and
VPBE_ENC_CUSTOM_TIMINGS is renamed to VPBE_ENC_DV_TIMINGS since the old
"CUSTOM_TIMINGS" name is deprecated in favor of "DV_TIMINGS".

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>